A possible transit event was detected in Hubble Space Telescope photometry of Alpha Centauri B while searching for transits of the planet candidate Alpha Centauri Bb. This may be due to the presence of a roughly Earth-sized planet in an orbit less than 20 days. Link to scientific paper Your name Note: Your commit will be vetted before it is merged into the public version. It is crucial that you include a link to a scientific publication. For more information on the meaning of the different datafields see the readme file in the Open Exoplanet Catalogue repository on github.